Separation of phenolic compounds from canned mandarin production wastewater by ultrafiltration and nanofiltration

A significant amount of Mandarin Wastewater is generated in the production of canned mandarin segments. To the best of our knowledge, the efficiency of membranes to recover phenolic compounds present in Mandarin Wastewater has never been studied before. The highest added value of polyphenols in cosmetic and pharmaceutical industries greatly encourages its purification as much as possible. In this study, different ultrafiltration and nanofiltration membranes were tested, and the best combination was a 5 kDa PES spiral-wound ultrafiltration membrane at 3 bar, followed by the NF270–2540 flat-sheet polypiperazine-amide nanofiltration membrane at 10 bar. Ultrafiltration was able to retain pigments (R = 90 %), pectins (R = 63 %), and sugars (R = 58 %). Then, phenolic compounds passed to the permeate (R = 5 %), which was used as the feed for nanofiltration. Finally, polyphenols were concentrated in the retentate of nanofiltration (R = 80 %), while sugars were partially separated in the permeate (R = 50 %). For a more detailed phenolic profile, liquid chromatography coupled to mass spectrometry was performed with the initial wastewater and the nanofiltration permeate. The results showed a significant rejection of most of the phenolic compounds (rejection >60 %) and the purity of the chemical family of flavonoids was doubled.